Purging choke



Jan. 28, 1964 F. PRICE 3,119,449

PURGING CHOKE Filed March 31, 1961 5/ dd 33 36' 7W 44 9 26' H 2/83 24 .9 2a" /5 /0 J4 32 i I l O 1/ J9 J] 4 in 5 W INVENTOR.

Fr eoexvck P/vce ATTORNEY United States Patent 3,119,449 PURGING CHOKE Frederick Price, 307 Boles St, Houston, Tex. Filed Mar. 31, 1961, Ser. No. 99,784 3 Claims. (Cl. 16691) This invention relates to automatic production volume controls or chokes and self-purging devices for oil wells.

There is usually located in the delivery pipe from the Well head or Christmas tree of an oil well an orifice or choke, which is proportioned in relation to the well pressure and flow to deliver the well fluid to the treating or storage point at the desired rate. This orifice or choke is usually replaceable and may be provided with a valve whereby its effective size may be varied as required. Such choke controls are entirely manual and, therefore, dependent upon the presence of a workman whenever a change is to be made.

When a well is shut in for a period of time and thereafter reopened, it frequently is found that the head pressure has dropped substantially. This may be due to the building up of a liquid head within the well, to sanding, or to the fact that gas has accumulated at the top of the well. Such reduced well head fluid delivery and/ or pressure, for any reason, if applied to a choke of the size as previously used when the Well was operating normally, will result in an inadequate and ineflicient flow from the well. for an interval beyond the desired normal setting to purge the well and thereby cause the well to return to its original delivery rate. However, the manual adjustment and re-adjustment of each well choke, first to effect the necessary purging and then to return the choke to its normal size, besides being time consuming, is neither reliable nor efiicient.

Another difiicul ty with present types of oil well delivery chokes is that clogging in the port, as due to sand, materially reduces the flow from the well and necessitates a complicated replacement of the choke.

Accordingly, an object of the present invention is to provide fully automatic means which is sensitive to subnormal or reduced well flow for temporarily increasing the size of the production choke and then resetting the choke for normal delivery when the well has purged itself.

Another object of the present invention is to provide a fully automatic purging choke having adjustable limit stops for varying the self-purging and normal positions of the valve in accordance with expected conditions.

Another object is to provide a novel purging choke device which can be readily substituted for the choke already provided, either fixed or adjustable.

Another object is to provide a purging choke device including simplified means for replacing the port element, as in case of excessive wear thereof.

These objects and others are attained by my novel purging choke, which consists, generally, of a port element and adaptor which may replace the fixed or variable choke already provided, thus utilizing the existing choke body. The novel control, which is threadedly secured to the choke body, slidably supports the actuating stem of a plunger which reciprocates axially through the mentioned port or orifice to vary the effective size or restrictive efiect thereof. The upstream face of the plunger is exposed to well head flow pressure which tends to close the valve. Fixed stops are provided adjacent the actuator stem which cooperate with the adjustable stops on the stem to vary the extreme positions of the plunger to provide both optimum purging and normal delivery conditions, as required. An adjustable spring urges the plunger toward its open position so that when the well -In such case, the choke may be openedice head flow pressure applied to the face of the plunger is below a predetermined value, the plunger will be opened to purge the well delivery.

In the accompanying drawings which illustrate the invention, FIG. 1 is a perspective view of a well head having the novel purging choke device applied thereto.

FIG. 2 is a vertical, longitudinal central section through the novel choke device, as viewed from the left-hand side of FIG. 1.

FIG. 1 shows a simplified well head 4 including a tubing valve having an actuator wheel 5, a wing valve in a body spool 6 and having an actuator wheel 7, and a tubing pressure gauge 8. A T-fitting 9 connects the wing valve body with delivery pipe 10 leading to a treating or storage point. The novel choke control, generally designated 11, is threadedly secured in one end of fitting 9, opposite pipe 10.

As shown in FIG. 2, there is provided at the end of pipe 10 an external thread 13 secured to fitting 9 and an internal thread 14 which receives the cylindrical valve port member 15, within which is located the ring 16 which forms the flow control or metering orifice or choke. Insert member 15 has recesses 17 at its inner end for cooperating with an applying tool.

Secured to the internal thread 18 in fitting 9 opposite thread 13 is a casting, generally designated 19, having an hexagonal external par-t 20 for receiving an applying wrench. Casting 19 has a central bore 21 which receives the plunger actuator stem 22 land a packing 23 secured in position by a threaded bushing 24.

At the right end of stem 22 is the tapered plunger 25 which extends axially through orifice 16 for controlling the effective size thereof. The annular shoulder 26 at the left end of plunger 25 is exposed to upstream pressure within a chamber 27, which communicates with the well head through passage 28 in the shank portion of fitting 9.

Threadedly secured to stem 22 and forming an extension thereof is an externally threaded sleeve 31 to which is also threadedly secured an extension stem 32 having a hex head 33 at its distal end. A coiled spring 34 is cornpressed between head 33 and a shoulder 35 at the end of a countersink 36 in the left end of a second body casting 37. Casting 37 has opposed radial projections 38 and 39 to which, respectively, are secured axially extending bars 41) and 41. A pair of parallel bars 40 are provided with a slot therebetween. The right-hand ends of bars 40 and 41 are provided with threaded extensions 42 and 43 received within suitable openings in radial projections 44 and 45 on casting 19 and firmly secured thereto by opposing nuts, as at 46 and 47.

Snugly and threadedly received on plunger actuator sleeve 31 are a pair of stop nuts 50 and 51. Nut 51) cooperates with the left-hand end 52 of casting 19, forming a fixed stop, to variably limit the closed or most restricted position of the valve. Nut 51 cooperates with the right-hand end 53 of casting 37 to variably limit the open or purging position of the valve. Also received on sleeve member 31 between the mentioned stop nuts is a third nut 55, normally fixed in position by means of a set screw 56 which also engages the extremity of valve actuator stem 22 to secure the same to threaded member 31. Projecting upwardly from nut 55 and in the slot between bars 40 is a pin 56 carrying an index pointer 57 at its upper extremity, which cooperates with index markings on the upper surfaces of bars 40 to indi cate the positioning of plunger 14.

Hinged to casting 19 is a sheet metal cover 64) which interiorly carries a spring latch 61, normally urged by a spring 62 into its latching position to underlie the left hand ends of bars 40. The purpose of the cover is to conceal adjusting stop nuts 50 and 51. Suitable means not here important are provided for withdrawing the latch so that the cover may be opened to expose the adjusting parts.

In order to install the novel purging choke device herein described, it is merely necessary to unscrew a plug usually provided in thread 18 at the left-hand end of fitting 9, which forms the choke body, and to withdraw the choke or other orifice part threadedly secured within the extremity of delivery pipe 10. A suitable part member 15, carrying metering orifice ring 16, will then be screwed into threads 14, wrench recesses 17 facilitating this operation. Next, casting 19, carrying the plunger control mechanism, is screwed into thread 18 from which the plug was removed. Stop nuts 50 and 51 are then adjusted by reference to indicator 57 to provide the desired normal choke position, with nut 50 in engagement with casting end 52, and the desired purging position, with out 51 in engagement with end 53 of casting 37. Then, when the wing and tubing valves are turned on, the well pressure applied to the upstream face 26 of valve 25 will urge the valve rightwardly toward its most restricting or normal production position. Due to the shape and disposition of the plunger, static as Well as dynamic forces in chamber 27 will tend to shift the plunger. A downstream gauge, of course, may be ob- .served to determine the delivered pressure, and this may he adjusted by varying the position of limit stop nut 50 for desired delivery rate. A further adjustment is pr vided at 33 upon the rotation of which the expansive force applied by compression spring 34, tending to open the valve against the upstream fluid pressure applied thereto, may be varied to determine the minimum well head fiow pressure for normal production. Thus, if the well head flow pressure drops below this set value, plunger 25 will open to increase the eifective size of the choke orifice. This will permit self purging of the well, as previously explained. When the well head flow pressure reaches the predetermined value, for which spring 34 is adjusted for normal production, plunger 25 will shift, automatically, to the normal choke position and, thereafter, will remain in this position for normal delivery of well fluids as long as the well head flow pressure is above the mentioned set value.

Thus, after a Well has been shut in for a period, it is only necessary for the operator to open the well valves, where upon the purging and resetting operations will occur automatically, accurately, and efiiciently, as required. Moreover, if the well flow pressure is excessively reduced for any reason, the choke is automatically enlarged a predetermined amount for self-purging action. The results achieved by use of the novel purging choke are substantially better than may be expected from-manual operation.

Various mechanical and other features and details may be modified as will occur to those skilled in the art, and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. A purging choke for a well comprising a body having parts for connection, respectively to the wellhead and .to a delivery pipe, means defining a flow-metering port in said body, a graduated plunger movable through said port defining means for selectively closing said means and varying the efiective capacity thereof between purging and normal flow metering positions, means resiliently urging said plunger toward said purging position, means responsive to flow pressure differential past and across said plunger for urging said plunger toward said normal metering position under normal flow conditions, and stop means adjustably positioned with respect to said plunger for varying both of said positions of said plunger.

2. A purging choke for an oil well comprising a body having upstream and downstream parts for connection, respectively, to a wellhead and a delivery pipe for well fluid, means defining aflow metering port in said body between said parts, a tapered plunger constantly extending into and shiftable axially with respect to said port defining means for selectively closing said means and varying the effective orifice size therethrough', said plunger being exposed to flow pressure differential across said means for shifting said plunger to a normal metering position responsive to predetermined flow from the well, spring means urging said plunger oppositely toward a more open, purging position, an actuating stem projecting from said plunger, fixed stop means adjacent said stern, adjustable stop elements on said stem cooperating with said stop means to vary said positions, and means to adjust said spring means to vary the response of said plunger to said plunger to said pressure differential.

3. In combination with an oil well'having a production pipe, an automatic purging choke comprising a body incorporated in said pipe, means defining a flow-metering port in said body, a plunger extending into said means and having a shoulder on the upstream side of said port means and exposed to flow pressure through said port to bias said plunger axially in the direction to reduce the efiective orifice size ofsaid means, a plunger actuator projecting from said plunger, spring means biasing said plunger in the opening direction for increasing the effective orifice size through said port defining means, means to adjust the biasing force exerted by said spring means to control the response of said plunger to pressure differential thereacross, and adjustable stop means cooperating with said,

actuator to limit the opening and closing movements of said plunger for automatically adjusting the delivery from the well under normal and subnormal production flow conditions;

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PURGING CHOKE FOR A WELL COMPRISING A BODY HAVING PARTS FOR CONNECTION, RESPECTIVELY TO THE WELLHEAD AND TO A DELIVERY PIPE, MEANS DEFINING A FLOW-METERING PORT IN SAID BODY, A GRADUATED PLUNGER MOVABLE THROUGH SAID PORT DEFINING MEANS FOR SELECTIVELY CLOSING SAID MEANS AND VARYING THE EFFECTIVE CAPACITY THEREOF BETWEEN PURGING AND NORMAL FLOW METERING POSITIONS, MEANS RESILIENTLY URGING SAID PLUNGER TOWARD SAID PURGING POSITION, MEANS RESPONSIVE TO FLOW PRESSURE DIFFERENTIAL PAST AND ACROSS 